Refactor: responsive upload page, fix warnings, CI/CD setup

- Fix MUI v4/React 18 StrictMode warnings (justify→justifyContent, Button migration)
- Responsive UploadDiary: footer visible without scroll, mobile layout centered, overview text hidden on mobile
- Fix Redux selector memoization with createSelector
- RSS sync: auto-refresh PosterSelector after sync, Snackbar feedback with film count
- Add .gitea/workflows/deploy.yml for tag-based CI/CD
- Fix nginx config (default.conf), increase Node heap for Docker build
- Update README

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -0,0 +1,34 @@
+name: Deploy Frontend
+
+on:
+  push:
+    tags:
+      - 'v*.*.*'
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Extract version tag
+        run: echo "VERSION_TAG=${GITHUB_REF_NAME}" >> $GITHUB_ENV
+
+      - name: Build Docker image
+        run: |
+          docker build \
+            --build-arg REACT_APP_API_URL="" \
+            -t poster-picker-frontend:latest \
+            -t poster-picker-frontend:${{ env.VERSION_TAG }} .
+
+      - name: Stop old container
+        run: |
+          cd ~/dev-server/poster-picker
+          docker compose stop frontend || true
+
+      - name: Start new container
+        run: |
+          cd ~/dev-server/poster-picker
+          docker compose up -d --no-build frontend